Gethen appears to have a surface gravity more or less similar to Earth and a human-compatible atmosphere (the Earth envoy sent there shows no sign of discomfort). Because of its cold climate, the planet is sometimes called "Winter".
Gethen's axis is not tilted (as is the case with Earth), but a relatively high orbital eccentricity produces global seasons. At the time of the story, Gethen is in the midst of an Ice Age (some local scientists believe it is near the end). The poles and a large portion of the land around them are permanently covered with glaciers, and even in the inhabited areas the climate can be extremely cold. In some places it is impossible to travel in winter, since the snow covers all roads. A summer day at 30 degrees Celsius is compared (by a Gethenian) to being inside a furnace.
Gethenians are physically and culturally adapted to cold; they tend to be of robust build and short stature, and they are familiar with the caloric yield of many different types of food. (The physical adaptations might be a product of genetic manipulation by the Hain, the species that "seeded" many worlds in the Ekumen with humanoid lifeforms.)
The inhabitants of Gethen are androgynes, biologically hermaphroditic humans; for approximately three weeks of each month they are biologically neuter, and for the remaining week are male or female, as determined by pheromonal negotiation with an interested sex partner. Thus each individual can both sire and bear children.
As for their appearance, Le Guin explains;
- In my first big science fiction novel, The Left Hand of Darkness, the only person from Earth is a black man, and everybody else in the book is Inuit (or Tibetan) brown.
Calendar and timekeeping
Gethen orbits its primary star once every 0.96 Earth years (8401 Earth hours). The planet rotates around its axis in 23.08 earth hours, so a Gethenian year consists of 364 local days.
The only natural satellite of the planet revolves around it in 26 local days, which constitutes a month. The year is divided into 14 of these lunar months. By fortunate coincidence, the deviation between this lunisolar calendar and the true solar year is small enough to require a correction only once every 200 years. Thus the days are synchronized with the moon phase every month.
Each day in a month has a unique name. Days are not grouped in weeks, but the month is evenly divided in two halves of 13 days each (the names of the days in the second half are derived regularly from those of the first half).
Gethenians further divide each day into ten parts or "hours", the first one starting at noon.
A very curious concept of dating is employed in Gethen, though this is only explained briefly in the book: the years are not numbered sequentially in increasing order, but the current year is always referred to as "Year One", and the others are counted as years before or after this standpoint. Historical records employ well-known events to mark (fixed) past dates.
Gethen has four continents and an archipelago. Two of the continents, Orgoreyn and Karhide, are connected. The action of the novel takes place here. The other continents are Sith and the Antarctic continent, Perunter. The planet is covered with ice everywhere beyond 45 degrees, and often down to 30 degrees.
Appearances in Le Guin's fiction
The main description of the people and culture is The Left Hand of Darkness. It gives their myths and legends, set amidst the story of a visitor from Earth.
Winter's King is a short story written earlier. It tells the story of Argaven, a Gethenian who visits another planet.
Coming of Age in Karhide was written 25 or 30 years later. It takes place after the events of Winter's King. It is mostly about an ordinary Gethenian discovering sex.
Another short story, The Shobies' Story, has Gethenians as part of a mixed Ekumen expedition to a new planet. Since they are now integrated into the Ekumen, it must take place after the other tales. In yet another tale, "Solitude", collected in The Birthday of the World, features a Gethenian scholar on an expedition.